No spark from 2&3

After following this forum, I was under the impression I had a bad pickup for 2&3. I replaced the coils with ones purchased here on the forum. Still the same issue. I swapped the connector from the TCI to the coils to make sure the coil was good, and it is. I swapped out a TCI box from a known good bike, same exact box, same issue. I get a spark it seems only when first pushing or releasing the starter button. Sometimes a very weak spark seems to show when cranking. I've run thru all the wires, none of them seem to ne bad. When tested with a meter, none of them show any measurable resistance so I believe they are good.

 

Man, a lot of spark problems here lately.


Did you follow this troubleshooting guide? http://www.xjbikes.com/Forums/viewtopic ... t=tci.html

It sounds like you're saying that you have tried new pickups and a known-good TCI and through all this you've always had spark only on 1&4.

That narrows things down quite a bit - albeit the hard way. The only possibilities are:

A) The 2/3 coil itself
B) The power wire to the 2/3 coil
C) The TCI-switched wire from the 2/3 coil to the TCI
D) The high tension wires or plug caps from the 2/3 coil to the plugs
E) A bad plug itself (since this is a wasted spark system, you may lose spark from both sides if one plug is bad or disconnected)

The troubleshooting guide has steps, starting at step 6, to help isolate this further.

 

When I swapped the plug at the coils, I then had spark. The 1/4 coil supply and trigger will fire either coil it is connected to. The power feed at both shows the same voltage. Resistance of both trigger wires from each coil to the tci plug are the same. One thing I noticed is that if I probe a test light to the power feed on the functioning coil, the light flickers at a very dim level. On the bad side, the light barely dims. This leads me to believe the oner side isn't consuming voltage. I have gone thru all the steps, and even spliced the harness for the pickup coils and wired in a known good coil. Still the same. I should also say that I made jumper wires. I used one to replace the trigger wire from tci to coil. I used the other to supply power to the feed side right from the battery.

 

OK, let's verify:

1. You tried a known good TCI and it made no difference.
2. If you swap the 2-ping connectors of the two coils (RedWhite/Orange) & (RedWhite/Grey), spark swaps from 1/4 to 2/3.

Are these correct? If so, there are only two possibilities:

A) The connection on the RedWhite supply wire to the 2/3 coil is bad.
You need a METER to measure voltage: red to RedWhite at the coil, black to chassis. Compare the readings obtained while cranking at the 2/3 coil to those at the 1/4 coil. You should see a slight drop at a working coil, but not much. Less than 10V while cranking would be bad.

or

B) The connection on the wire running from the 2/3 coil to the TCI is bad (Orange or Grey - can't remember which is which). Use your METER to measure resistance from the Orange or Grey wire pin at the coil (connectors disconnected) to the corresponding pin at the TCI 4-pin plug. Compare to the resistance reading for the 1/4 coil's wire. They should be similar and should be less than 1 Ohm.

 

I did check the resistance of the trigger wires for each coil, and both were very similar. A voltage check to the supply wire for each coil while NOT cranking shows system voltage at both. I haven't checked while cranking, but will tomorrow. I switched the pickup coil input pins on the 6 pin connector and the spark swapped from one to the other. I don't remember the result of swapping at the 4 pin, but will try it tomorrow. My only question is, if it is the supply wire, what is the remedy? I was under the impression they were spliced together in the main harness. Also, if it is the supply wire, why do I get good spark when swapping pins on the 6 pin input side?

 

OK. I am definitely confused as to what you have and have not done.

1. Earlier you said "When I swapped the plug at the coils, I then had spark. The 1/4 coil supply and trigger will fire either coil it is connected to. " I would expect here you're talking about the RedWhite/Orange and RedWhite/Grey connectors at the coils?

2. Now you're saying that when you swapped Orange and Grey at the 6-pin connector of the TCI spark switched from 1/4 to 2/3?

This doesn't make sense. Something is missing from the equation, or I am misunderstanding #1.

If #2 is the correct statement here, and that's the same thing you were talking about in #1, then you do indeed have a bad pickup or bad wiring from the pickup to the TCI. If #1 and #2 are both correct, then something else would have had to change between the two steps.

 

Question 1- Yes. I swapped the connectors to the coils. Spark stayed with the 1/4 supply connector. This was done with all else in it's original position.

Question 2- Yes. Switching the two pins at the 6 pin connector also swaps spark on the coils.

I used an inline spark tester rather than an extra plug.

 

OK. Makes sense. Bad pickup or bad pickup wiring. That's all it can be.

 

Trouble is, I just installed a used one my friend bought through a member here. Its odd this one failed in exactly the same coil. I cut the one that was working off the old set and soldered it in place of the one that was not working. Now I'm confused. I guess I have a couple other questions. On the new one, there is a frame ground under the kickstand, and a bullet connector which plugs into a black/red wire. There are also a few wires coming off that harness that go to bullet connectors under the seat. I made a new frame ground, the one which has the half circle fitting on the end. I used a self tapping screw to mount that to the frame. Any chance these are an issue? Not even sure what they do.

 

If you have consistent spark on 1/4 and not on 2/3, then it's extremely unlikely something common to both channels, like the ground, is going to be the issue. The fact that you swapped a pickup in the past makes me think that you should double-check that soldering and the rest of the wiring that was disturbed at the time.

 

The only wiring I don't know about are the four bullet connectors on the pickup harness. One down by the quicksand, and three up by the box which go to wires under the seat. If these are running thru this harness, what are they for? I have used jumpers to replace all the possible suspect wires, even though they all Ohm out good. It's odd that the entire circuit from the tci to the spark plugs functions when the pickup input is reversed. This makes me believe the circuits are fine, but the signal related to the gray wire is at fault. If not a pickup coil, and the wire from the coil to the tci is good, what else can there be? So far, I thought swapping the inputs and getting spark on 2/3 proved the 2/3 circuits good after the tci. That being assumed, if the pickup coil and input wiring to the tci is good, is there any other influence I am unaware of?

 

Your results do prove that the TCI, the ignition coils, and their wiring are all good.

The problem has to be with the 2/3 pickup coil or its wiring. Either the pickup coil is bad, or its wiring is bad, or it's connected incorrectly. There are three wires for the two pickups: Grey for one pickup's signal, Orange for the other pickup's signal, and a common ground for both pickups (Black, IIRC).

If you disconnect the 6-pin plug at the TCI and measure resistance from the common (Black?) wire to Orange what resistance do you read? What about from the common wire to Grey?

Also, are you sure that the 2/3 pickup is correctly mounted to the timing plate (same gap relative to the reluctor as the 1/4 pickup)?

 

pickups have same gap, I measured with a feeler gauge and set them the same. Of the four wires in the 6 pin connector, when disconnected the solid black wire and the gray wire have continuity, about .6 ohms. That's it. The orange wire, which is the input for the 1/4 coil which is working, doesn't show continuity. Could this be that the gray wire is shorted to ground?

 

You shouldn't be checking continuity, you should be checking resistance. However, if you're seeing .6 Ohms between the Gray wire and the Black wire, then I think you found your problem, and, yes, the Gray pickup wire is shorted somewhere.

 

I should have clarified. I used the continuity function to find out if there was continuity at all, then my meter autoranges to resistance giving me a reading of just over .6 Ohms. I will pull the pickup off and see if I can find the short. I was initially under the impression that I should be looking for continuity, and focusing on resistance values, so imagine my surprise when the only wire showing continuity happened to be the one which doesn't fire. I will pull the harness off and check the wires. Thanks, I'll keep you posted. Appreciate the help. P.S. I noticed the routing of the P/U harness makes it impossible to get it off the bike without moving the engine, since the harness won't fit thru a small area underneath where the wires are routed from the factory. I wrapped the harness in aircraft tape and rerouted it, so it shouldn't be a hard check except unwrapping all that tape, lol.

 

Strangest thing. I pulled the harness and started trimming back the plastic casing. About halfway through, the orange wire was severed. Could be the guy who pulled it off to sell it had accidentally pinched or cut the wire taking it off. I soldered the wire, and bang.....spark at all 4. Strange thing is, it's the orange wire. On the coils, that's the one that always worked, it was the gray wire that didn't. The wires are in the same positions as they are on the other bike here, which is the same year, make, model. It bothers me that I don't understand, but I guess I'm happy that it works. I'm going to finish going thru the carbs and reassemble tonight. Thanks for your help. If you can explain the mystery, I would sure love to know.